1. Field of the Invention
The present invention relates to an ink set characterized in that a treatment liquid including particle is combined with a recording liquid including resin-coated colorant, a specific treatment liquid for the ink set, a specific recording liquid for the ink set, an ink-jet printing method for forming an image by adhering the treatment liquid and the recording liquid to a recording medium, an ink-jet printer, a cartridge for receiving therein the treatment liquid and the recording liquid, and an ink-jet record article produced by using the ink-jet printer.
2. Description of the Related Art
An ink-jet printing method for carrying out an image recording by using, as a liquid droplet, a recording liquid including a colorant is excellent in that the above printing method has a simple printing mechanism and is free from noise.
On the other hand, the above image printing method is likely to cause an image failure whose typical example is a character feathering (hereinafter referred to as feathering) attributable to some combinations with a recording medium, thus greatly deteriorating image quality. Trying to decrease the feathering by suppressing ink permeability is carried out. In this case, however, deteriorated dryness of the ink may cause failures such as: touching a print after printing may allow the ink to adhere to a hand, the image may be stained, and the like.
Moreover, printing a color image overlaps different colors of ink one after another, thus causing bleeding of color ink at a color boundary portion or causing a non-uniform mixture (hereinafter referred to as “color bleeding”), thus substantially decreasing the image quality, which is problematical. Increasing the ink permeability is being tried for solving the problem, namely, for decreasing the color bleeding. In this case, however, the colorant entering the recording medium may decrease image density and increase permeation of the ink to a back of a recording medium, thereby making it difficult to carry out a favorable double-sided printing.
Therefore, the image forming method is desired to solve the above problems at the same time and increase the image quality.
To the above problems, a method of combining a recording liquid with a treatment liquid (which includes particle) is proposed. For example, an ink-jet printing method is disclosed (for example, refer to Japanese Patent Application Laid-Open (JP-A) No. 04-259590 (Scope of claim for patent on line 1 to line 7 in column 1 on page 2, paragraph[0010], paragraph [0015] and paragraph [0022])) in which a colorless liquid including silica particle is adhered to a recording medium, followed by adhering of a non-aqueous recording liquid including oil black. Moreover, an ink-jet printing method is disclosed (for example, refer to Japanese Patent Application Laid-Open (JP-A) No. 06-92010 (claim 1 on line 2 to line 8 in column 1 on page 2 and paragraph [0010])) in which resin particle, titanium dioxide particle or the like, or a solution including the above particles and binder polymer is applied or injected before a recording liquid including pigment and resin is discharged. Moreover, an image forming method is disclosed (for example, refer to Japanese Patent Application Laid-Open (JP-A) No. 11-228890 (Scope of claim for patent on line 1 to line 27 in column 1 on page 2)) in which an image is formed on a recording medium by discharging a colorless ink-jet treatment liquid (including anionic metal oxide colloid) separately from discharging of an ink (including colorant but not resin content), followed by mixing.
Each of Japanese Patent Application Laid-Open (JP-A) No. 04-259590 and Japanese Patent Application Laid-Open (JP-A) No. 11-228890, however, discloses a combination of the recording liquid (including anionic colorant) with the treatment liquid (including anionic particle), thus making aggregation effect and absorption effect of the colorant unobtainable, resulting in failure in suppression of feathering and color bleeding. Japanese Patent Application Laid-Open (JP-A) No. 06-92010 disclosing a combination of anionic colorant with cationic titanium dioxide can feature a certain effect in terms of aggregation and absorption of the colorant, however, does not show a sufficient effect for suppressing feathering and color bleeding. Use of low viscosity ink and low viscosity treatment liquid in Patent Japanese Patent Application Laid-Open (JP-A) No. 06-92010 may flow out aggregation component, thus causing failure in sufficient suppression of feathering and color bleeding, which is problematical.
Moreover, an image forming method is disclosed (for example, refer to Japanese Patent Application Laid-Open (JP-A) No. 2001-199149 (claim 2on line 13 to line 21 in column 1 on page 2)) having a step of absorbing to a particle surface a colorant that is in a single-molecule state in a liquid droplet and a step of causing aggregation of particles having the surface to which the colorant is absorbed. Moreover, an ink set is disclosed (for example, refer to Japanese Patent Application Laid-Open (JP-A) No. 2001-199150 (claim 1 on line 2 to line 9 in column 1 on page 2)) in which pH of a mixture that is an ink and liquid composition mixed substantially at a ratio of 1 to 1 by weight causes colorant aggregation. Moreover, a liquid composition is disclosed (for example, refer to Japanese Patent Application Laid-Open (JP-A) No. 2001-199151 (claim 1 on line 2 to line 7 in column 1 on page 2)) which is included in such a state that a particle having a surface charged with an opposite polarity to that of aqueous ink is dispersed. Although showing a certain effect in terms of color aggregation and color absorption, each of the above documents is, however, unable to bring about a sufficient effect for suppressing feathering and color bleeding.
Moreover, using the treatment liquid including particle, the above proposals have another problem in fusibility of the recording liquid. Specifically, the treatment liquid and the recording liquid are adhered to the recording medium and then a vehicle permeates to the recording medium, thus accumulating a mixture of the particle with the colorant on a surface of the recording medium. The thus formed accumulation is mechanically vulnerable, thereby it may be easily removed by rubbing by hand and the like. This may stain a user's hand by ink or backface of overlapped prints, resulting in failure of wear resistance.
In terms of shortage of wear resistance, an ink-jet printing method is disclosed (for example, refer to International Publication No. WO00/06390 (claim 1 on line 2 to line 6 on page 2)) in which i) a first liquid including a reaction agent which causes aggregation when contacting a polymer particle and/or an ink composition, and ii) the ink composition including the polymer particle are caused to adhere to a recording medium, to thereby carry out printing. In a constitution in International Publication No. WO00/06390, a colorant in itself is free from a function for improving wear resistance, thereby a large amount of polymer particles is needed for obtaining a sufficient wear resistance. Putting a large amount of polymer particles may, however, cause such side effects as decreased discharge stability, decreased preservability stability, increased viscosity and the like, resulting in an unsolved problem.
Moreover, an ink-jet print printing method is disclosed (for example, refer to Japanese Patent Application Laid-Open (JP-A) No. 2001-171095 (claim 1 on line 2 to line 7 in column 1 on page 2)) in which a semi-transparent white ink which is composed of i) an inorganic oxide pigment, ii) dispersant and/or high molecular compound, iii) an water-soluble organic solvent and iv) water is caused to fixed in advance to a recording medium, and an water-soluble dye ink is used for recording an image. In a constitution under Japanese Patent Application Laid-Open (JP-A) No. 2001-171095, however, a colorant in itself is free from a function for improving wear resistance, therefore a large amount of polymer particles are needed for obtaining a sufficient wear resistance, resulting in an unsolved problem.
Moreover, an ink-jet printing method is disclosed (for example, refer to Japanese Patent (JP-B) No. 2667401 (claim 1 on line 2 to line 7 in column 1 on page 1)) in which, so as to form an image, a colorless or hypochromic liquid including two or more cationic groups per molecule is caused to adhere to a recording medium, then the liquid is permeated in the recording medium, then the liquid is present in the recording medium, then the liquid disappears from a surface of the recording medium, and soon after the above steps, an ink including anionic dye is caused to adhere to a portion to which the liquid is caused to adhere. Moreover, an ink-jet printing method is disclosed (for example, refer to Japanese Patent (JP-B) No. 2675001 (claim 1 on line 2 to line 7 in column 1 on page 1)) in which, so as to form an image, a colorless or hypochromic liquid including a multivalent metal salt is caused to adhere to a recording medium, then the liquid is permeated in the recording medium, then the liquid is present in the recording medium, then the liquid disappears from a surface of the recording medium, and soon after the above steps, an ink including oxide-group including dye is caused to adhere to a portion to which the liquid is caused to adhere. Moreover, an ink-jet printing method is disclosed (for example, refer to Japanese Patent (JP-B) No. 2711098 (claim 1 on line 2 to line 9 in column 1 on page 1.)) in which, so as to form an image, a colorless or hypochromic liquid including a quaternary ammonium salt or an amine salt whose molecule has therein one or more groups selected from i) an alkyl group with carbon atoms 4 or more, ii) an alkenyl group and iii) an aryl group is caused to adhere to a recording medium, then the thus adhered liquid is permeated in the recording medium, then the liquid disappears from a surface of the recording medium, and soon after the above steps, an ink including soluble dye including acidic group is caused to adhere to a portion to which the liquid is caused to adhere.
However, using the treatment liquid that does not include particle, the methods disclosed in the above documents are insufficient for improving image density, decreasing character feathering and decreasing color mixture. Moreover, use of the dye whose colorant is not of resin-coated type is insufficient in terms of wear resistance on image forming portion.